1. Field of the Invention
This invention relates in general to exercise treadmills, and more particularly, to a motor-less exercise treadmill having a geared flywheel system to improve the momentary reaction of the tread-belt of the treadmill in response to a user increasing or decreasing his or her stride speed thereon.
For the fifth consecutive year, walking ranks No. 1 in growth among 40 sports and fitness activities surveyed by the National Sporting Goods Association. In 1992 treadmills were rated the largest selling fitness product with 9.3 million users.
2. Description Of The Related Art
In 1993 the motor-less treadmill was popularized by the television infomercial by such companies as Nordic Track of Minnesota and the La Fonda Group of California, models "Walk Fit" and "Walk To The Music" respectively, to name but a few.
These prior art devices are substantially similar in their design and their function. Generally, the prior art devices comprise a frame for mounting the components of the device which include; a front roller having one or more flywheels connected or integrally attached thereto; a back roller; a slider bed mounted on the frame intermediate the forward and back rollers; and a endless tread-belt entraining the front roller, slider bed and back roller to provide a revolving tread-belt that is manipulated into motion by the user while walking or running thereon.
The objective of these prior art devices is to provide an affordable and aerobic exercise effective indoor walking or running treadmill device whereon a user may walk or run while maintaining his or her body geographically stationary.
The failure of the prior art to provide an effective aerobic exercise treadmill device, is best illustrated with a brief description of the normal walking biomechanics.
There are three phases to normal walking; "the heel strike phase", wherein the advancing foot strikes the exercise surface with the heel which smoothly transitions to; the "foot flat phase", wherein the advancing foot moves backward, in relation to the torso, and the leg is fully extended with the entire sole of the foot in contact with the exercise surface which smoothly transitions to; the "push off phase", wherein the leg continues backward and the torso is propelled forward by the pushing off from the exercise surface with the big toe of the now trailing foot.
In order to generate a non-jarring, natural walking action, all three of the biomechanical phases of normal walking must occur in a coordinated transition, smoothly and without interruption, with the left and right legs reciprocating into and out from the three phases of walking.
The devices of the prior art do not provide the smooth transition of the three phases of normal walking due to their inefficient flywheel designs.
Walking on the tread-belt of the prior art devices demonstrates a sticking and binding of the tread-belt when the user's entire body weight is focused on the tread-belt during the "foot flat phase" of normal walking. The greater the user's weight the more demonstrable the sticking and binding of the tread-belt. The sticking and binding of the tread-belt relates to the inefficiency of the flywheel to deliver an effective inertia and momentum to the tread-belt. Sticking and binding of the tread-belt interrupts the smooth coordinated transition between the three phases of normal walking and thus predisposes the user's foot, knee, pelvis and lower spinal joints to injury. The risk of joint injury is substantially increased when the tread-belt sticks or stops abruptly thereby subjecting the knee joint, on the weight bearing side, to hyperextension strain which compromises the ligaments and hamstring muscles of the knee joint.
Furthermore, the flywheel design of the prior art fails to adequately control the tread-belt reaction in response to the user accelerating or decelerating his or her stride speed. This results in the tendency for the tread-belt to indiscriminately accelerate in response to the user pushing through the sticking point and during the push off phase of normal walking. The acceleration of the tread-belt being out of synchrony with the user's stride speed thus creating the potential for the user to fall forwardly.
Still a further drawback of the prior art devices relates to the inefficient tread-belt momentum supplied by the flywheel whereby the user is forced to stabilize his or her upper body by holding onto front stabilization rails, or in the case of the Nordic Track design by leaning into the a hip stabilizing pad, in order to manipulate the tread-belt into a smooth steady motion.
In order to overcome the inefficiencies of the flywheel design of the prior art a substantially larger and heavier flywheel would be required. A larger and heavier flywheel would generate a greater centrifugal force and thereby provide a greater inertia and momentum to the tread-belt. However, including a larger and heavier flywheel is prohibited by both the cost and the design parameters of the prior art devices.
All of the problems inherent to the prior art flywheel designs are overcome with a electric motor driven tread-belt since the speed of the tread-belt is in a direct relationship with the speed of the motor.